Radiation chemistry in ammonia-water ices
- Astrochemistry Laboratory, NASA GSFC, Code 691, Greenbelt, Maryland 20775 (United States)
- Laboratory for Atomic and Surface Physics, Engineering Physics, University of Virginia, Charlottesville, Virginia 22904 (United States)
We studied the effects of 100 keV proton irradiation on films of ammonia-water mixtures between 20 and 120 K. Irradiation destroys ammonia, leading to the formation and trapping of H{sub 2}, N{sub 2}, NO, and N{sub 2}O, the formation of cavities containing radiolytic gases, and ejection of molecules by sputtering. Using infrared spectroscopy, we show that at all temperatures the destruction of ammonia is substantial, but at higher temperatures (120 K), it is nearly complete ({approx}97% destroyed) after a fluence of 10{sup 16} ions/cm{sup 2}. Using mass spectroscopy and microbalance gravimetry, we measure the sputtering yield of our sample and the main components of the sputtered flux. We find that the sputtering yield depends on fluence. At low temperatures, the yield is very low initially and increases quadratically with fluence, while at 120 K the yield is constant and higher initially. The increase in the sputtering yield with fluence is explained by the formation and trapping of the ammonia decay products, N{sub 2} and H{sub 2}, which are seen to be ejected from the ice at all temperatures.
- OSTI ID:
- 21559832
- Journal Information:
- Journal of Chemical Physics, Vol. 132, Issue 5; Other Information: DOI: 10.1063/1.3308484; (c) 2010 American Institute of Physics; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTROSCOPY
AMMONIA
CHEMICAL ANALYSIS
HYDROGEN
ICE
INFRARED SPECTRA
IRRADIATION
MASS SPECTROSCOPY
MICROBALANCES
MIXTURES
NITRIC OXIDE
NITROUS OXIDE
PROTONS
RADIATION CHEMISTRY
RADIOLYSIS
SPUTTERING
TEMPERATURE RANGE 0065-0273 K
WATER
YIELDS
BALANCES
BARYONS
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DISPERSIONS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
HADRONS
HYDRIDES
HYDROGEN COMPOUNDS
MEASURING INSTRUMENTS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NONMETALS
NUCLEONS
OXIDES
OXYGEN COMPOUNDS
RADIATION EFFECTS
SPECTRA
SPECTROSCOPY
TEMPERATURE RANGE
WEIGHT INDICATORS